The system engineering of fire protection in vehicles, in particular track-guided vehicles such as railway vehicles, is of increasing importance, as is also borne out for example by the ratification of numerous national and international standards and directives in recent years. For example, the TSI (Technical Specification for Interoperability), the EN45545 and the EN50553 define measures outlining the extent to which rail vehicles are to be equipped with active fire protection systems. These new provisions serve personnel safety, increasing safety in tunnels and ultimately also protecting railway vehicle property. Accordingly, there is an increased need for effective fire protection systems for railway vehicles or similar track-guided vehicles.
However, the complexity of track-guided vehicles, in particular railway vehicles, usually requires an individual fire protection concept which is not so readily comparable to the solutions known in structural fire protection since there are clearly different risks in railway vehicles.
In addition to the early detection of fire with aspirative smoke detectors and automatic smoke detectors, automatic fire suppression in particular also plays a substantial role. Typical areas of operation thereto are electrical equipment, control cabinets, roof and underfloor fittings, sleeper or couchette cars, passenger compartments, drive assemblies and other areas of increased fire risk.
Inert gas extinguishing technology is particularly recommended for protecting against fire in sectioned areas such control and electrical cabinets since the necessary extinguishing concentration is able to be readily maintained in such sectioned areas.
In inert gas extinguishing technology, the protected area (sectioned area) is at least partially flooded with an oxygen-displacing gas such as, for example, nitrogen, argon or CO2 (hereinafter also referred to as “inert gas”) and thus rendered inert.
The preventative or extinguishing effect resulting from rendering a protected area inert is based on the principle of oxygen displacement. As is known, normal ambient air consists of about 21% oxygen by volume, about 78% nitrogen by volume and about 1% by volume of other gases. In order to effectively lower the risk of a fire breaking out in a given protected area, such as for example in an enclosed room, the oxygen content within the relevant area is decreased by introducing inert gas or an inert gas mixture respectively such as e.g. nitrogen. As regards extinguishing fire in the case of most solid matter, an extinguishing effect is for example known to begin when the percentage of oxygen drops below about 15% by volume. Depending upon the flammable substances situated in the protected area, it may be necessary to further lower the percentage of oxygen to, for example, 12% by volume.
Particularly when used in track-guided vehicles, preventive inertization of the relevant target areas is advantageous upon start-up. Due to a respective vehicle's mobility and minimum available space, there are also only few possibilities for implementing effectual fire prevention and extinguishing system. Furthermore, such a system must not substantially impact either the vehicle's normal operation nor its safety-relevant functions.
Existing systems for preventing and/or extinguishing fires within vehicles and/or aircraft provide in particular for supplying nitrogen-enriched gas mixtures in storage tanks and/or by means of additional generators. Thus, to be able to ensure sufficient inertization of enclosed rooms, conventional fire prevention and extinguishing systems require a great deal of space within the respective vehicle or can only be used for rooms of small spatial volumes. Therefore, a larger installation space in terms of volume is needed to accommodate the components of an in-vehicle fire prevention and extinguishing system. Moreover, such prior art gas or water droplet extinguishing systems are only activated once a fire has already developed and the associated components in the respective area of the vehicle have already suffered damage.
An alternative is the system known from DE 10 2008 047 663 which provides a controlled nitrogen atmosphere for transporting large amounts of fruits using a ship's existing on-board compressed air system. This system can however also be used to produce nitrogen for tanker loading tanks to prevent risks of fire and explosion.